A power amplifier used for a base station while performing radio communication requires small size and high performance in terms of costs. Meanwhile, for radio communication such as mobile phones and the like, a broad-banded and high-efficiency power amplifier is required as the dedicated power amplifier for a base station because of accelerate of its communication speed and becoming broad-banded. There is an EER (Envelope Elimination and Restoration) method as one of the methods to meet this requirement, one example of which is disclosed in, for example, a specification of U.S. Pat. No. 6,256,482.
A power supply circuit using the EER method should convert a broadband envelope signal into power of a power amplifier with high efficiency. There is a method disclosed in, for example, Japanese Patent Application National Publication No. 2003-533116 of a power supply circuit that amplifies a broadband envelope signal with high efficiency.